Multiwell plates, also called micro titre plates, have been used for many years in laboratories for the simultaneous analysis of a number of samples. Typical formats include 4, 24, 48, 96 and 384 wells per plate. Initially, these plates had solid bases and liquid samples were pipetted into and out of the wells.
Subsequently, plates with wells provided with a lower well through hole (known as a “drip” if it is provided with downward protruding lips) pierced through the bottom surface. These micro titre plates allowed the samples to flow through the wells which permitted larger sample volumes to be processed (since the sample size was no longer limited to the capacity of the well).
Later developments of micro titre plates were provided with filter or membrane wells in which each well was provided with a microporous filter or membrane which extended over the cross-section of the well such that all of the sample passing through the well had to pass through the filter or membrane. These micro titre plates are also called micro titre filter plates.
A further development of a micro titre plate comprises wells with a lower well through hole or drip and a filter or membrane and which wells are each at least partly filled with a media such as a chromatographic gel or slurry or chromatographic particles.
Different screening processes that could be performed on such micro titre plates are for example screening of/for: i) conditions for optimal binding capacity, ii) most efficient wash buffers for washing off impurities from chromatography resin; iii) most efficient eluting solution; iv) selectivity obtained using different ligands, v) best resin either from capacity or purity perspective. Considering the multi well format of microtiter plates, if processes under different conditions need to be studied there are different possibilities to change conditions on a single plate. For example the concentration of the sample added can be changed, the composition of the buffer in which the sample is dissolved can be changed, the effect of overall time of contact between the sample and a chromatography resin can be studied, or any combinations of the above.
High throughput studies of chromatographic separations using microtiter plates filled with chromatography resin proved highly efficient in reducing time and sample requirements necessary for development of large scale purification processes. While the studies reported have focused on specific aspects of chromatographic steps, a very few studies have been reported focusing on understanding physics of the separation processes studied. From understanding the separation process perspective the knowledge of adsorption isotherm is of paramount importance. Adsorption isotherms are fundamental property of any separation systems, and an isotherm should always be determined in order to full understand governing principles behind an adsorption process.